Acetophenone \Ac`e*to*phe"none\ (-f[=e]"n[=o]n), n. [Acetic + phenyl + one.] (Chem.) A crystalline ketone, {CH3.CO.C6H5}, which may be obtained by the dry distillation of a mixture of the calcium salts of acetic and benzoic acids. It is used as a hypnotic under the name of {hypnone}. [Webster 1913 Suppl.]